Abstract: A low speed region position estimating portion is designed to be suitable for when the motor is operating in a low speed region, and estimates a low speed estimated rotational position ?^L. A high speed region position estimating portion is designed to be suitable for when the motor is operating in a high speed region, and estimates a high speed estimated rotational position ?^H. A dividing portion obtains a divided estimated rotational position ?^M by internally dividing the low speed estimated rotational position ?^L and the high speed estimated rotational position ?^H. A rotation speed calculating portion obtains a rotation speed ? of a rotor based on an output signal from a steering sensor. The rotational position of the rotor is then obtained by selecting one of i) the low speed estimated rotational position ?^L, the high speed estimated rotational position ?^H, or the divided estimated rotational position ?^M, based on that rotation speed ?.

Abstract: A low speed region position estimating portion is designed to be suitable for when the motor is operating in a low speed region, and estimates a low speed estimated rotational position ??L. A high speed region position estimating portion is designed to be suitable for when the motor is operating in a high speed region, and estimates a high speed estimated rotational position ??H. A dividing portion obtains a divided estimated rotational position ??M by internally dividing the low speed estimated rotational position ??L and the high speed estimated rotational position ??H. A rotation speed calculating portion obtains a rotation speed ? of a rotor based on an output signal from a steering sensor. The rotational position of the rotor is then obtained by selecting one of i) the low speed estimated rotational position ??L, the high speed estimated rotational position ??H, or the divided estimated rotational position ??M, based on that rotation speed ?.